HpARI is a protein secreted by the mouse parasite Heligmosomoides polygyrus. The mature protein HpARI, containing three predicted Complement Control Protein (CCP)-like modules (also known as Short Consensus Repeats (SCRs) or sushi-domains), suppresses type 2 (allergic) immune responses through interference in the interleukin-33 (IL-33) pathway. During cell damage, HpARI gains access to the nucleus of necrotic cells, where it binds directly to IL-33 and nuclear DNA, preventing secretion and binding of IL-33 to its receptor. HpARI is a new type of reagent to prevent IL-33-mediated pathology.